During ordinary use of scoop loaders of the type carried by a vehicle, usually comprising a front end scoop, considerable difficulty is encountered in keeping the materials which are initially picked up by the bucket from falling back out of the bucket while the materials are being moved. Although it is relatively easy when loading granular materials or small objects to substantially fill the bucket, to tilt it back and to pick it up without much spillage, it becomes very much more difficult to pick up a load when the materials being loaded contain larger pieces of odd shapes, for instance, such as scraps of wood or pieces of wall board as encountered while scoping the debris resulting from the demolition of a building. Moreover, the scoop loader is frequently used for moving materials which simply do not fit into the bucket at all, such as long boards, or large area materials such as plywood sheet, etc.
As a consequence a number of different devices have been proposed for retaining the materials picked up by the bucket, and for clamping these materials in the case of relatively large pieces such as boards and sheets. U.S. Pat. No. 3,057,496 to Garske shows a front end loader having an hydraulically operated clamping blade which can be moved to a substantially closed position in which it contacts the front lip of the bucket, or can be opened to a raised position in which it extends forwardly of the bucket slightly above horizontal. There is no provision for placing the clamping blade in an out-of-service position where it does not interfere with the use of the device when it is not needed.
U.S. Pat. No. 3,451,575 to Petro shows another front end loader having a grill which can be lowered over the front of the bucket without entering into the bucket, the grill serving to prevent discharge of the materials within the bucket prior to intended discharge thereof. U.S. Pat. No. 3,077,999 to Svoboda shows still another front end loader which is functionally similar to that shown in the Petro patent.
There are also a number of patents showing devices attached to buckets which serve to scrape a vertical wall of materials downwardly, for instance, as shown in U.S. Pat. Nos. 3,252,606 to Pryor and 3,148,787 to Clark et al.